New salt of abexinostat, associated crystalline form, a process for their preparation and pharmaceutical compositions containing them

ABSTRACT

Abexinostat tosylate of formula (II): 
     
       
         
         
             
             
         
       
     
     and its crystalline form I characterised by its X-ray powder diffraction diagram, its Raman spectrum and its solid-state  13 C CP/MAS NMR spectrum.
 
Medicinal products containing the same which are useful in the treatment of cancer.

The present invention relates toN-hydroxy-4-{2-[3-(N,N-dimethylaminomethyl)-benzofuran-2-ylcarbonylamino]ethoxy}benzamidetosylate, or a solvate thereof.

Alternatively, the subject-matter of the invention relates to a tosylatesalt of abexinostat of formula (I):

More especially, the invention is directed to the salt of formula (II):

The present invention relates also to crystalline form I ofN-hydroxy-4-{2-[3-(N,N-dimethylaminomethyl)benzofuran-2-ylcarbonylamino]ethoxy}benzamidetosylate, to a process for its preparation and also to pharmaceuticalcompositions comprising it.

N-hydroxy-4-{2-[3-(N,N-dimethylaminomethyl)benzofuran-2-ylcarbonylamino]ethoxy}-benzamide,also known as abexinostat, is a historic deacetylase (HDAC) inhibitordescribed in patent application WO2004/092115. it allows inhibition ofcell growth and induces apoptosis in cultured tumour cells in vitro, andit inhibits tumour growth in vivo in xenograft models (Buggy et al.,Mol. Cancer Ther 2006 5(5) 1309). In view of its pharmacologicalprofile, abexinostat is intended for use in the treatment of cancer.

From the industrial point of view it is imperative to be able tosynthesise the compound with excellent purity, especially in a perfectlyreproducible form, having valuable characteristics of dissolution,filtration, drying, ease of formulation and stability allowing itsprolonged storage without particular requirements for temperature,light, humidity or oxygen levels.

Patent application WO2004/092115 describes two different routes forobtaining abexinostat. In both cases, 3-methyl-benzofuran-2-carboxylicacid is used as starting material, but functionalisation of this centralnucleus by the dimethylaminomethyl group in the 3-position is carriedout at different stages in the synthesis process, namely before or aftercoupling of the benzofuran-2-carboxylic acid compound with methyl4-(2aminoethoxy)benzoate. Obtaining abexinostat hydrochloride isspecifically described in the WO2004/092115 application. However, usingthis salt on an industrial scale is problematic because of itshygroscopic properties.

The present invention describes a process for obtaining abexinostattosylate (abexinostat 4-methylbenzenesulfonate) in a well-defined,perfectly reproducible crystalline form having very good stability thatis compatible with the industrial constraints of preparation (especiallydrying) and storage of pharmaceutical compositions.

Crystalline form I of abexinostat tosylate is characterised by an X-raypowder diffraction diagram having the following diffraction lines(Bragg's angle 2 theta, expressed in degrees) ±0.2°); 6.50; 9.94; 11.35;12.33; 14.08; 18.95; 21.08; 27.05. Even more especially, crystallineform I of abexinostat tosylate is characterised by the followingdiffraction lines: 6.50; 9.94; 11.35; 12.33; 14.08; 18.95; 19.61; 19.96;21.08; 22.82; 23.61; 27.05.

More specifically, crystalline form I of abexinostat tosylate ischaracterised by the X-ray powder diffraction diagram hereinbelow,measured using a PANalytical X′Pert Pro MPD diffractometer with anX′Celerator detector and expressed in terms of line position (Bragg'sangle 2 theta, expressed in degrees ±0.2°) and interplanar distance d(expressed in Å):

Angle 2-theta Interplanar Line no. (degrees) distance (Å) 1 6.50 13.5812 9.94 8.894 3 11.35 7.789 4 12.33 7.173 5 14.08 6.285 6 18.95 4.683 719.61 4.526 8 19.96 4.449 9 21.08 4.215 10 22.82 3.897 11 23.61 3.768 1227.05 3.296

Besides that, crystalline form I of abexinostat tosylate has beencharacterised by Raman spectroscopy. Significant peaks were observed atthe following positions: 940 cm⁻¹, 1088 cm⁻¹, 1132 cm⁻¹, 1242 cm⁻¹, 1360cm⁻¹, 1608 cm⁻¹.

Alternatively, crystalline form 1 of abexinostat tosylate may becharacterised by the X-ray powder diffraction diagram which includes the12 significant lines given hereinabove and also by a Raman spectrumhaving a significant peak at the position 1608 cm⁻¹.

Finally, crystalline form I of abexinostat tosylate has also beencharacterised by solid-state NMR spectroscopy, Significant peaks wereobserved at 121.2 ppm, 122.1 ppm, 123.5 ppm, 126.0 ppm, 126.8 ppm, 128.2ppm, 128.9 ppm, 143.4 ppm, 144.6 ppm, 153.8 ppm, 159 ppm, 161.2 ppm and162.1 ppm.

More specifically, the ¹³C CP/MAS (Cross Polarization Magic AngleSpinning) spectra have the following peaks (expressed in ppm±0.2 ppm):

Chemical shift Peak no. (ppm) 1 162.1 2 161.2 3 159.0 4 153.8 5 144.6 6143.4 7 128.9 8 128.2 9 126.8 10 126.0 11 123.5 12 122.1 13 121.3 1465.9 15 50.6 16 46.9 17 45.0 18 21.9

The invention relates also to a process for the preparation ofcrystalline form I of abexinostat tosylate, which process ischaracterised in that abexinostat is crystallised from a polar medium inthe presence of paro-toluenesulphonic acid. Preferably, the polar mediumis composed of one or more solvents selected from water, alcoholsketones and esters, it being understood that:

-   -   “alcohols” means C₁-C₆ alcohols such as methanol, ethanol,        propanol, isopropanol, butanol, isobutanol, pentanol,        2-pentanol, 3-pentanol, isopentanol, hexanol,    -   “ketones” means a C₃-C₆ ketone such as acetone, methyl ethyl        ketone, 2-pentanone, 3-pentanone, 3-methyl-2-butanone,        2-hexanone, 3-hexanone, ethyl isopropyl ketone, methyl isopropyl        ketone, 2,2-dimethyl-3-butanone,    -   “esters” means C₃-C₈ ester such as ethyl formate, isopropyl        formate, ethyl acetate, propyl acetate, isopropyl acetate, butyl        acetate, isobutyl acetate, tert-butyl acetate, pentyl acetate,        isopentyl acetate, hexyl acetate.

Preferred alcohols are ethanol and isopropanol. Among the preferredsolvents preference will also be given to acetone and methyl ethylketone among the ketones and to ethyl acetate among the esters.

Alternatively, the polar medium is a binary mixture, one of theconstituents of which is water. Even more preferably, the polar mediumis a binary mixture selected from: acetone/water, ethanol/water,isopropanol/water and methyl ethyl ketone/water.

In the crystallisation process according to the invention, abexinostat(free base) obtained by any process may be used.

The invention relates also to another process for the preparation ofcrystalline form I of abexinostat tosylate, in which process thecrystallisation is seeded using a very small amount of crystalline formI of abexinostat tosylate.

In this second crystallisation process according to the invention,abexinostat (free base) obtained by any process may also be used.

Obtaining crystalline form I of abexinostat tosylate has the advantageof making it possible to prepare pharmaceutical formulations having aconsistent and reproducible composition and having good characteristicsof dissolution and stability, which is especially advantageous when theformulations are intended for oral administration. More specifically,use of crystalline form I of abexinostat tosylate is especially valuablein an industrial context in view of its low hygroscopicity.

Crystalline form I of abexinostat tosylate is intended for the treatmentof cancer, more especially the treatment of a carcinoma, a tumour, aneoplasm, a lymphoma, a melanoma, a glioma, a sarcoma or a blastoma.

The invention relates also to pharmaceutical compositions comprising, asactive ingredient, tosylate salt of abexinostat, even more especiallycrystalline form I of abexinostat tosylate, together with one or moreappropriate, non-toxic, inert excipients. Among the pharmaceuticalcompositions according to the invention there may be more especiallymentioned those that are suitable for oral, parenteral (intravenous orsubcutaneous) or nasal administration, tablets or dragées, granules,sublingual tablets, capsules, lozenges, suppositories, creams,ointments, dermal gels, injectable preparations, drinkable suspensionsand chewing gums.

Preference is given to pharmaceutical compositions administered via theoral route.

The useful dosage varies according to the sex, age and weight of thepatient, the administration route, the nature of the cancer and anyassociated treatments; the useful dosage ranges from 20 mg to 480 mg ofN-hydroxy-4-{2-[3-(N,N-dimethylaminomethyl)-benzofuran-2-ylcarbonylamino]ethoxy}benzamideper day expressed in terms of the free base.

The Examples hereinbelow illustrate the invention but do not limit it inany way.

EXAMPLE 1 Process for obtaining crystalline form of abexinostat tosylate

1.66 kg of abexinostat (free base) are placed in 9.48 kg of a mixture ofisopropanol/water (50/50 weight/weight) at ambient temperature,para-Toluenesulphonic acid monohydrate (0.83 kg) in 2.36 kg of water isadded at ambient temperature. The mixture is then heated at 75° C. for30 minutes before being cooled to 0° C. When crystallisation iscomplete, the suspension is filtered at 20° C. After drying, crystallineform I of abexinostat tosylate is obtained in a yield of about 85% andwith a purity greater than 99%. The solid was characterised by the X-raypowder diffraction diagram, Raman spectrum and NMR spectrum as set outin Examples 3-5 and 6 hereinbelow.

EXAMPLE 2 Process for obtaining crystalline form I of abexinostattosylate (seeding)

33.9 kg of abexinostat (free base) are placed in 170 kg of a mixture ofisopropanol/water (45.6/54.4 weight/weight) at ambient temperature. Asolution composed of para-toluenesulphonic acid monohydrate (17.06 kg)in water (24.1 kg) is added. The mixture is then heated at 70-75° C.,cooled and seeded with 1.935 kg of crystalline form I of abexinostattosylate. The suspension is then filtered at 20° C. After drying,crystalline form I of abexinostat tosylate is obtained in a yield ofabout 86% and with a purity greater than 99%. The solid wascharacterised by the X-ray powder diffraction diagram. Raman spectrumand NMR spectrum as set out in Examples 3-5 and 6 hereinbelow.

EXAMPLE 3 Crystalline form I of aboxinostat tosylate (X-ray powderdiffraction diagram)

Recording of the data was carried out using a PANalytical X′Pert Pro MPDdiffractometer with an X′Celerator detector under the followingconditions:

-   -   Voltage 45 kV, current 40 mA,    -   Mounting: theta/theta,    -   Anode: copper,    -   K alpha-1 wavelength: 1.54060 Å,    -   K alpha-2 wavelength: 1.54443 Å,    -   K alpha-2/K alpha-1 ratio: 0.5,    -   Measurement mode: continuous from 3° to 55° (Bragg's angle 2        theta) in increments of 0.017°,    -   Measurement time per step: 35.53 s.

The X-ray powder diffraction diagram of form I of abexinostat tosylateobtained according to the process of Example 1 or 2 is expressed interms of line position (Bragg's angle 2 theta, expressed in degrees±0.2°), interplanar distance (expressed in Å) and relative intensity(expressed as a percentage relative to the most intense line). Thesignificant lines have been collated in the following table:

Angle 2-theta Interplanar Relative Line no. (degrees) distance (Å)intensity (%) 1 6.50 13.581 75.6 2 9.94 8.894 58.4 3 11.35 7.789 19.1 412.33 7.173 23.7 5 14.08 6.285 33.1 6 18.95 4.683 100 7 19.61 4.526 53.98 19.96 4.449 50.9 9 21.08 4.215 93.5 10 22.82 3.897 28.5 11 23.61 3.76832.6 12 27.05 3.296 16.0

EXAMPLE 4 Crystalline form I of abexinostat tosylate (crystal unit cell)

A saturated solution of abexinostat tosylate in 2,2,2-trifluoroethanolis prepared by stirring a suspension for 24 hours at ambienttemperature, followed by filtration. 1 mL of the resulting solution isthen poured into a 1.8-mL HPLC vial, to which 0.25 mL of water is added.The solution is maintained at ambient temperature for 75 minutes. Aftercentrifuging and then drying, the solid is isolated for analysis. Fromamong the crystals obtained a crystal of sufficient quality is taken forsingle-crystal X-ray diffraction analysis. The crystalline structure ofthe above single crystal was determined using a Bruker Kappa CCDdiffractometer equipped with an FR590 generator having a molybdenumanticathode (λMoKα1=0.7093 Å) with an angular range from 2° to 27.5° interms of θ. The following parameters were established:

-   -   crystal unit cell: triclinic    -   unit cell parameters: a=10.467 Å, b=14.631 Å, c=20.159 Å,        α=73.971°, β=79.040°, γ=72.683°    -   space group: P-1    -   number of molecules in the unit cell: 4    -   volume of the unit cell: V_(unit cell)=2813.0 Å³    -   density: d=1.345 g/cm³.

EXAMPLE 5 Crystalline form I of abexinostat tosylate (Raman spectrum)

Form I of abexinostat tosylate was characterised by Raman spectroscopy.The spectra were recorded in diffuse reflectance mode (Raman Station400, PerkinElmer) using a 785 nm laser. The signal was recorded by a CCDdetector. The wavelength shift depends on the material and ischaracteristic of that material, which allows analysis of the chemicalcomposition and of the molecular arrangement of the sample studied. Thespectra were acquired with maximum power (100% laser capacity), a spotsize of 100 μm, twenty exposures of 2 seconds and a spectral resolutionof 2 cm⁻¹. The spectral range explored ranges from 0 to 3278 cm⁻¹.

Significant peaks were observed at the following positions: 940 cm⁻¹,1088 cm⁻¹, 1132 cm⁻¹, 1242 cm⁻¹, 1360 cm⁻¹, 1608 cm⁻¹,

EXAMPLE 6 Crystalline form I of abexinostat tosylate (solid NMRspectrum)

Form I of abexinostat tosylate was also characterised by solid-state NMRspectroscopy. The ¹³C NMR spectra were recorded at ambient temperatureusing a Bruker SB Avance spectrometer with a 4-mm CP/MAS SB VTN typeprobe under the following conditions:

-   -   Frequency: 125.76 MHz,    -   Spectral width: 40 kHz,    -   Magic angle spinning rate of sample: 10 kHz,    -   Pulse sequence: CP (Cross Polarization) with SPINAL64 decoupling        (decoupling power: 80 kHz),    -   Repetition delay: 10 s.    -   Acquisition time: 35 ms,    -   Contact time: 4 ms,    -   Number of scans: 4096.

An apodisation function (“5 Hz line broadening” is applied to thecollected signal before the Fourier transform. The spectra therebyobtained were referenced relative to a sample of adamantane (thehighest-frequency peak of adamantane has a chemical shift of 38:48 ppm).

The peaks observed have been collated in the following table (expressedin ppm±0.2 ppm):

Chemical shift Peak no. (ppm) 1 162.1 2 161.2 3 159.0 4 153.8 5 144.6 6143.4 7 128.9 8 128.2 9 126.8 10 126.0 11 123.5 12 122.1 13 121.3 1465.9 15 50.6 16 46.9 17 45.0 18 21.9

EXAMPLE 8 Pharmaceutical composition

Formula for the preparation of 1000 tablets each containing 100 mg ofabexinostat (expressed in terms of the base equivalent):

Abexinostat tosylate 143.4 g Lactose monohydrate 213.1 g Magnesiumstearate 2.5 g Maize starch 75 g Maltodextrin 50 g Anhydrous colloidalsilica 1 g Sodium carboxymethylcellulose 15 g

EXAMPLE 8 Hygroscopicity

Hygroscopicity of form I of abexinostat tosylate was assessed usingdynamic vapor sorption (DVS) technique. 5 to 10 mg of the drug substancetest sample were accurately weighed into a DVS sample pan working at 25°C. under controlled humidity. The mass variation was recorded whilstdrying under 0 per cent RH (relative humidity) and during two subsequentcycles of increasing and decreasing linear variations of relativehumidity in the range 0-90 per cent RH at a rate of 10 per cent perhour. The relative humidity was maintained constant when it reachedeither 0 or 90 per cent RH until the mass variation was less than 0.002per cent per minute within a limit of time of 15 h.

An increase in weight lower than 0.5% was detected by DVS analysis whena sample was exposed to relative humidities from 0% to 90% at 25° C.

1.N-hydroxy-4-{2-[3-(N,N-dimethylaminomethyl)benzofuran-2ylcarbonylamino]-ethoxy}benzamidetosylate, or a solvate thereof.
 2. A tosylate salt of abexinostat offormula (I):


3. A pharmaceutical composition comprising, as active ingredientabexinostat tosylate according to claim 1, in combination with one ormore pharmaceutically acceptable excipients.
 4. A method of treatingcancer in a subject in need thereof, comprising administration of aneffective amount of the pharmaceutical composition according to claim 3.5. The method according to claim 4, wherein the cancer is a carcinoma, atumour, a neoplasm, a lymphoma, a melanoma, a glioma, a sarcoma or ablastoma.
 6. A process for the preparation of crystalline form I ofabexinostat tosylate, having an X-ray powder diffraction diagram havingthe following diffraction lines (Bragg's angle 2 theta, expressed indegrees ±0.2°): 6.50; 9.94; 11.35; 12.33; 14.08; 18.95; 21.08; 27.05,wherein the abexinostat is crystallised in the presence ofpara-toluenesulphonic acid in a polar medium and wherein thecrystallisation is seeded using a very small amount of crystalline formI of abexinostat tosylate.